Trying hard to avoid being that infamous 98-pound weakling? Pumping iron will only get you so far. First, you need to increase your total intake of calories. The biggest returns come from filling up on muscle-building foods--those packed with proteins or amino acids, carbohydrates and other nutrients that are particularly beneficial to muscle development. Here are four you should add to your diet when you're trying to bulk up:

Milk

Despite the bad rap milk has received in the past, athletes and bodybuilders still keep it on their list of preferred muscle-building foods. And for good reason. Milk is rich in proteins that contain all the amino acids your body needs. An important group of proteins in milk are caseins, which are reputed for their role in growth and development.

Studies on resistance training involving healthy young men have shown that drinking two cups of fat-free milk immediately before and one hour after exercise produced more muscle mass than drinking a soy protein or carbohydrate beverage. Whey protein in milk increases fat loss. In addition, calcium in milk blocks a hormone that makes your body store fat, increasing its power to give you a more ripped physique. Milk also helps to protect against muscle atrophy or wasting.

Eggs

Eggs are powerful muscle-building foods and are no longer shunned for their cholesterol content. If you were thinking of breaking a few eggs into a glass for a muscle-building shake like Rocky, go ahead. Ounce for ounce, eggs are one of the richest protein sources available containing all the amino acids your body needs for building muscle. They are rich in an essential amino acid called leucine, which researchers believe has a critical role in how muscles utilize glucose, and in post-exercise recovery.

A successful muscle-building program also takes a lot of energy. Eggs provide a sustained source of energy without affecting blood sugar and insulin levels.

Carbohydrates

Carbohydrates are also important muscle-building foods. They provide fuel for your muscles during your workout, but your body stores only a limited amount of carbohydrates in the form of glycogen. Although exercise increases the ability of muscles to store glycogen, this supply is depleted during workouts. Once that happens, fatigue sets in and compromises your workout.

The more vigorous or intense your workout is, the more you'll need to refuel your glycogen stores. In general, but especially as muscle-building foods, low-fat, whole grain carbohydrates that are high in dietary fiber, vitamins and minerals are the preferred choice over refined sugar-filled carbohydrates.

Omega 3 fatty acids

A study published in the Journal of Physiology revealed that omega-3 fatty acids--abundant in fatty fish - support the metabolism of muscle proteins. As you get older, your body's ability to convert nutrients in food into muscle proteins declines, possibly due to insulin resistance associated with aging. Omega-3 fatty acids boost glucose metabolism in people and animals with insulin resistance, so the researchers set out to determine if the these nutrients had the same effect on protein metabolism.

They fed fish-oil supplements to steers, and after five weeks the animals had increased insulin sensitivity and improved protein metabolism. They were able to convert twice the amount of amino acids to synthesize proteins, particularly in muscles. Researchers concluded that omega 3 fatty acids--in combination with a physical training program--could also benefit athletes trying to increase muscle mass. The best way to get these muscle-building foods is to eat three or more servings of a variety of fish each week.

Sources:

Université Laval Institute of Nutraceutics and Functional Foods press release "Study Shows Marine Omega-3 Fatty Acids Have Positive Effect on Muscle Mass."

Journal: Nutrition Today, Vol. 44 Issue 1, pp43-48,

Date: Jan/Feb 2009

Study: Egg Protein as a Source of Power, Strength and Energy.
Website: http://journals.lww.com/nutritiontodayonline/pages/articleviewer.aspx?year=2009&issue=01000&article=00013&type=abstract

Authors: Layman DK, Rodriguez, NR